OBJECTIVE: This study aimed to examine the reliability of supine medicine ball throw peak force and rate of force development (RFD) measurements. A secondary aim was to investigate the correlations between these measurements and vertical jump height.
METHODS: Twenty young women (21±3 years) reported for experimental testing on two different occasions. Supine medicine ball throw assessments were performed during each testing session to assess peak force, RFDmax, and RFD at specific percentages of peak force (RFD30% and RFD40-80%). Vertical jumps were performed on a jump mat. The jump mat measured vertical jump height based on flight time.
RESULTS: Good intraclass correlation coefficients (≥0.82) and coefficients of variation (≤14.0%) were observed between sessions for peak force, RFDmax, and RFD40-80%, but not for RFD30% (0.55, 27.2%). There were significant correlations between jump height and peak force (r=0.483, P=0.031), RFDmax (r=0.484, P=0.031), and RFD40-80% (r=0.491, P=0.028). There was no significant correlation between jump height and RFD30% (r=0.359, P=0.120).
CONCLUSIONS: Our results showed that supine medicine ball throw peak force, RFDmax, and RFD40-80% were reliable measures for assessing upper-body explosive strength in young adults. These measurements were significantly associated with vertical jump height and therefore, may be effective predictors of one\'s athletic ability.

We have investigated the magnitude of circadian variation in Isokinetic and Isometric strength of the knee extensors and flexors, as well as back squat and bench press performance using the MuscleLab force velocity transducer. Ten resistance-trained males (mean±SD: age 21.5 ± 1.1 years; body mass 78.3 ± 5.2 kg; height 1.71 ± 0.07 m) underwent a) three to four familiarization sessions on each dynamometer and b) four sessions at different times of day (03:00, 09:00, 15:00 and 21:00 h). Each session was administered in a counterbalanced order and included a period when Perceived onset of mood states (POMS), then rectal and muscle temperature (Trec, Tm) was measured at rest, after which a 5-min standardized 150 W warm-up was performed on a cycle ergometer. Once completed, Isokinetic (60 and 240°·s-1 for extension and flexion) and Isometric dynamometry with peak torque (PT), time-to-peak-torque (tPT) and peak force (PF) and % activation was measured. Lastly, Trec and Tm were measured before the bench press (at 30, 50 and 70 kg) and back squat (at 40, 60 and 80 kg) exercises. A linear encoder was attached to an Olympic bar used for the exercises and average force (AF), peak velocity (PV) and time-to-peak-velocity (tPV) were measured (MuscleLab software; MuscleLab Technology, Langesund, Norway) during the concentric phase of the movements. Five-min recovery was allowed between each set with three repetitions being completed. General linear models with repeated measures and cosinor analysis were used to analyse the data. Values for Trec and Tm at rest were higher in the evening compared to morning values (Acrophase Φ: 16:35 and 17:03 h, Amplitude A: 0.30 and 0.23°C, Mesor M: 36.64 and 37.43°C, p < 0.05). Vigor, happy and fatigue mood states responses showed Φ 16:11 and 16:03 h and 02:05 h respectively. Circadian rhythms were apparent for all variables irrespective of equipment used where AF, PF and PT values peaked between 16:18 and 18:34 h; PV, tPV and tPT peaked between 05:54 and 08:03 h (p < 0.05). In summary, circadian rhythms in force output (force, torque, power, and velocity) were shown for isokinetic, isometric dynamometers and complex multi-joint movements (using a linear encoder); where tPV and tPT occur in the morning compared to the evening. Circadian rhythms in strength can be detected using a portable, low-cost instrument that shows similar cosinor characteristics as established dynamometers. Hence, muscle-strength can be measured in a manner that is more directly transferable to the world of athletic and sports performance.

BACKGROUND: The Apple Watch (AW) Series 1 provides energy expenditure (EE) for wheelchair users but was found to be inaccurate with an error of approximately 30%, and the corresponding error for heart rate (HR) provided by the Fitbit Charge 2 was approximately 10% to 20%. Improved accuracy of estimated EE and HR is expected with newer editions of these smart watches (SWs).
OBJECTIVE: This study aims to assess the accuracy of the AW Series 4 (wheelchair-specific setting) and the Fitbit Versa (treadmill running mode) for estimating EE and HR during wheelchair propulsion at different intensities.
METHODS: Data from 20 manual wheelchair users (male: n=11, female: n=9; body mass: mean 75, SD 19 kg) and 20 people without a disability (male: n=11, female: n=9; body mass: mean 75, SD 11 kg) were included. Three 4-minute wheelchair propulsion stages at increasing speed were performed on 3 separate test days (0.5%, 2.5%, or 5% incline), while EE and HR were collected by criterion devices and the AW or Fitbit. The mean absolute percentage error (MAPE) was used to indicate the absolute agreement between the criterion device and SWs for EE and HR. Additionally, linear mixed model analyses assessed the effect of exercise intensity, sex, and group on the SW error. Interclass correlation coefficients were used to assess relative agreement between criterion devices and SWs.
RESULTS: The AW underestimated EE with MAPEs of 29.2% (SD 22%) in wheelchair users and 30% (SD 12%) in people without a disability. The Fitbit overestimated EE with MAPEs of 73.9% (SD 7%) in wheelchair users and 44.7% (SD 38%) in people without a disability. Both SWs underestimated HR. The device error for EE and HR increased with intensity for both SWs (all comparisons: P<.001), and the only significant difference between groups was found for HR in the AW (-5.27 beats/min for wheelchair users; P=.02). There was a significant effect of sex on the estimation error in EE, with worse accuracy for the AW (-0.69 kcal/min; P<.001) and better accuracy for the Fitbit (-2.08 kcal/min; P<.001) in female participants. For HR, sex differences were found only for the AW, with a smaller error in female participants (5.23 beats/min; P=.02). Interclass correlation coefficients showed poor to moderate relative agreement for both SWs apart from 2 stage-incline combinations (AW: 0.12-0.57 for EE and 0.11-0.86 for HR; Fitbit: 0.06-0.85 for EE and 0.03-0.29 for HR).
CONCLUSIONS: Neither the AW nor Fitbit were sufficiently accurate for estimating EE or HR during wheelchair propulsion. The AW underestimated EE and the Fitbit overestimated EE, and both SWs underestimated HR. Caution is hence required when using SWs as a tool for training intensity regulation and energy balance or imbalance in wheelchair users.

BACKGROUND: The application of blood flow restriction (BFR) to low-intensity exercise may be able to increase strength not only in the trained limb but also in the homologous untrained limb. Whether this effect is repeatable and how that change compares to that observed with higher intensity exercise is unknown.
OBJECTIVE: Examine whether low-intensity training with BFR enhances the cross-education of strength compared to exercise without BFR and maximal efforts.
METHODS: A total of 179 participants completed the 6-week study, with 135 individuals performing isometric handgrip training over 18 sessions. Participants were randomly assigned to one of four groups: 1) low-intensity (4 × 2 min of 30% MVC; LI, n = 47), 2) low-intensity with blood flow restriction (LI + 50% arterial occlusion pressure; LI-BFR, n = 41), 3) maximal effort (4 × 5 s of 100% MVC; MAX, n = 47), and 4) non-exercise control (CON, n = 44).
RESULTS: LI-BFR was the only group that observed a cross-education in strength (CON: 0.64 SD 2.9 kg, LI: 0.95 SD 3.6 kg, BFR-LI: 2.7 SD 3.3 kg, MAX: 0.80 SD 3.1 kg). In the trained hand, MAX observed the greatest change in strength (4.8 SD 3.3 kg) followed by LI-BFR (2.8 SD 4.0 kg). LI was not different from CON. Muscle thickness did not change in the untrained arm, but ulna muscle thickness was increased within the trained arm of the LI-BFR group (0.06 SD 0.11 cm).
CONCLUSIONS: Incorporating BFR into low-intensity isometric training led to a cross-education effect on strength that was greater than all other groups (including high-intensity training).

Motion analysis during activities of daily living has been conducted in numerous studies. However, information is lacking regarding age-related differences that affect clinical assessment and treatment goals. This study aimed to examine the effect of age on kinematics during activities of daily living. Three-dimensional motions of the shoulder, elbow, neck, and trunk of 12 younger adults (age, 29.8 ± 5.4 years; 7 men and 5 women) and 10 older adults (age, 69.5 ± 4.9 years; 6 men and 4 women) were measured during the acts of reaching for a table, bringing a glass to the mouth for drinking, wiping the buttocks, tying shoelaces, washing hair, washing the axilla, reaching for a high shelf, and reaching for the floor. The ranges of motion and sequential joint angles were compared between age groups by using discrete analysis and statistical parametric mapping, respectively. The ranges of motion of all joint angles in older and younger adults were comparable in the drinking, washing hair, washing the axilla, and reaching for the floor tasks. Statistical parametric mapping indicated that older adults had significantly poorer neck extension than did younger adults during the drinking (67-92% cycle time) and tying shoelaces (64-95% cycle time) tasks. Kinematics were mostly maintained in healthy older adults during activities of daily living. However, reduced motions were confirmed later during some tasks. The results indicated that existing knowledge combined with the current findings, which take age into account, could be used in clinical settings to assess the kinematics of activities of daily living and set treatment goals.

Becker\'s naevus also known as Becker\'s melanosis (BM) or pigmented hairy epidermal naevus is a cutaneous hamartoma with brown hyperpigmentation and hypertrichosis. It commonly occurs during adolescence and rarely at birth. It usually affects young post-pubertal males and has a prevalence of 0.5%. A naevus usually consists of a circumscribed, unilateral, irregularly shaped, hyperpigmented spot usually located around the anterior upper body, with or without hypertrichosis and/or acneiform lesions. Sometimes developmental abnormalities can occur with Becker\'s naevus, which is called Becker\'s naevus syndrome (BNS). Becker\'s naevus was of atypical presentation in two patients over the forearm and leg. Hence, these case reports gain importance.

OBJECTIVE: To investigate the efficacy of using Ratings of Perceived Exertion (RPE) to prescribe and regulate a 4-week handcycle training intervention.
METHODS: Thirty active adults, untrained in upper body endurance exercise, were divided into three groups to complete a 4-week intervention: (i) RPE-guided training (n = 10; 2 female), (ii) power output (PO)-guided (n = 10; 2 female) training, or (iii) non-training control (n = 10; 4 female). Training groups performed three sessions of handcycling each week. Oxygen uptake ([Formula: see text]), heart rate (HR), and Feeling Scale (FS) rating were collected during training sessions. RPE-guided training was performed at RPE 13. PO-guided training was matched for percentage of peak PO per session, based upon that achieved by the RPE-guided training group.
RESULTS: There were no differences in percentage of peak [Formula: see text] (66 ± 13% vs 61 ± 9%, p = 0.22), peak HR (75 ± 8% vs 71 ± 6%, p = 0.11) or FS rating (1.2 ± 1.9 vs 0.8 ± 1.6, p = 0.48) between RPE- and PO-guided training, respectively. The average coefficient of variation in percentage of peak HR between consecutive training sessions was 2.8% during RPE-guided training, and 3.4% during PO-guided training.
CONCLUSIONS: Moderate-vigorous intensity handcycling exercise can be prescribed effectively using RPE across a chronic training intervention, suggesting utility for practitioners in a variety of rehabilitation settings.

To investigate the usefulness of inertial measurement units (IMUs) in the assessment of motor function of the upper limb (UL) in accordance with the international classification of functioning (ICF).
PubMed; Scopus; Embase; WoS and PEDro databases were searched from inception to 1 February 2022.
The current systematic review follows PRISMA recommendations. Articles including IMU assessment of UL in stroke individuals have been included and divided into four ICF categories (b710, b735, b760, d445). We used correlation meta-analysis to pool the Fisher Z-score of each correlation between kinematics and clinical assessment.
A total of 35 articles, involving 475 patients, met the inclusion criteria. In the included studies, IMUs have been employed to assess the mobility of joint functions (n = 6), muscle tone functions (n = 4), control of voluntary movement functions (n = 15), and hand and arm use (n = 15). A significant correlation was found in overall meta-analysis based on 10 studies, involving 213 subjects: (r = 0.69) (95% CI: 0.69/0.98; p < 0.001) as in the d445 (r = 0.71) and b760 (r = 0.64) ICF domains, with no heterogeneity across the studies.
The literature supports the integration of IMUs and conventional clinical assessment in functional evaluation of the UL after a stroke. The use of a limited number of wearable sensors can provide additional kinematic features of UL in all investigated ICF domains, especially in the ADL tasks when a strong correlation with clinical evaluation was found.

Previous work has shown that the mean continuous relative phase and coordination variability of lower limbs are modified in older adults when walking.
Here, we propose to understand the extent to which such control mechanisms for upper limbs are present during gait. Specifically, we seek to understand if aging and gait speed constraints influence the interjoint control of upper limbs during walking.
This observational study evaluated thirty-three participants, divided into older (n = 20, age 66.4 ± 4.3 years; mass: 77.2 ± 14.2 kg; height: 165 ± 9.20 cm) and young adults (n = 13, age 29.5 ± 4.7 years; mass 75.5 ± 9.6 kg; height: 172 ± 6.24 cm) were asked to walk at 0.28, 0.83, 1.38 m.s-1 on a level treadmill while their segmental movements were simultaneously registered with 3D motion capture system. We calculated the mean continuous relative phase and coordination variability (continuous relative phase variability) in elbow-shoulder and shoulder-hip pairs, and a generalized estimating equation was used to test the main and interaction effects of age and speed.
Older adults had a reduced continuous relative phase (more in-phase coordination) of upper limbs at whole stance for elbow-shoulder, at loading response for shoulder-hip, at mid-stance and terminal stance for elbow-shoulder and shoulder-hip in comparison to young adults at different speeds (p < 0.05). The coordination variability of upper limbs was greater (higher continuous relative phase variability) in older than young adults at 0.28 and 1.38 m.s-1.
These findings substantiate the altered motor control role of upper limbs in gait aging, suggesting that lower self-selected speed may be related to the reduced ability to control arm movement during the intermediate phases of gait.

A musculoskeletal (MSK) model is a valuable tool for assessing complex biomechanical problems, estimating joint torques during motion, optimizing motion in sports, and designing exoskeletons and prostheses. This study proposes an open-source upper body MSK model that supports biomechanical analysis of human motion. The MSK model of the upper body consists of 8 body segments (torso, head, left/right upper arm, left/right forearm, and left/right hand). The model has 20 degrees of freedom (DoFs) and 40 muscle torque generators (MTGs), which are constructed using experimental data. The model is adjustable for different anthropometric measurements and subject body characteristics: sex, age, body mass, height, dominant side, and physical activity. Joint limits are modeled using experimental dynamometer data within the proposed multi-DoF MTG model. The model equations are verified by simulating the joint range of motion (ROM) and torque; all simulation results have a good agreement with previously published research.